Coil transportation systems have, for the most part, one or two reel or wind-off devices and one or two coiling devices for winding of strip-shaped material into coils. The coil conveyance or transport, meaning the coil supply and removal, is performed through intermediate buffers and by coil trolleys with coil depositories cooperating with these buffers, as well as with the reel-off and reel-up devices for improved operational sequence.
Induction loop controlled air cushion vehicles for coil conveyance have been used (a) to obviate the need for additional conveyance devices such as walking beam or pallet conveyors if, for instance, the coil depository cannot be served by overhead cranes, b) for simplified integration of intermediate stations, (c) for removal of the baling cord, (d) for coil measuring and (e) weighing or preparation. In such cases, one works, for instance, with three buffer stations and two air cushion vehicles, which convey the coils having weights up to 40 tons laterally within two workshop halls. The air cushion vehicles are controlled by an induction loop embedded in the floor and are made to move by an electronic data process order from a governing or overriding process computer.
The travel drive consists of two hard rubber wheels, which are powered by two regulatable electric motors. The vehicle is provided with four air cushions in order to obtain a stable position of the load, which are centrally supplied with compressed air through a feed hose. If the air supply is switched on, the annularly shaped air cushions, consisting of a fiber-reinforced rubber material, expand and fill-up the spacing between the vehicle and the floor. As soon as the air cushions are sealed against the ground, the air pressure rises in the area bounded by the air cushion or bellows and the air cushions carrying the load are lifted up or rise.
If the air cushions are completely filled with air, a small quantity of air escapes outwardly beneath and around the air cushions. The load or the vehicle then "floats" on the produced air layer, practically without any friction (compare the product information Mover, "Air Layer Module.") The air cushion requires two antennas, one at the front and one at the rear for being guided by the induction loop. The antennas scan the eddy currents and are connected with on board computers for information or measured value-processing.
However, there are various disadvantages inherent in such known devices. The measured value processing and the vehicle control are complicated and expensive and the system is malfunction-prone. Furthermore an air cushion vehicle leaves the desired traveling path.
It is therefore an object of the to create a coil transportation or conveying system with air cushion vehicles, which permits a more malfunction-free operational sequence and in an economical manner.